Susan,
A traditional recipe for Persian ink is:
500 g water
5 g salt
250 g gum arabic
30 g gall apples, grilled and powderized
40 g iron sulphate (copperas/ferrous sulphate/green vitriol)
30 g honey
This gives a very glossy ink, and that can be part of
the problem. In dry weather, the ink might shrink
up and begin curling off the burnished paper, surface
sized with egg white.
Excess sulfuric acid, from the iron sulfate, can also
eat away the surface of the paper (or parchment, in
the case of mss. on animal skin) allowing the letters
to drop off the page.
Jack
>I have a page from a Koran, probably 18th or 19th c.,
>manuscript not printed, in which some of the letters
>have simply vanished, taking the paper with them!
>Susan Fatemi,
>susanf@peer.berkeley.edu
Thompson Conservation Lab.
7549 N. Fenwick
Portland, OR 97217
503/735-3942 (voice/fax)
http://www.teleport.com/~tcl
"The lyfe so short; the craft so long to lerne"
Chaucer, Parlement of Foules, 1386
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